Fluid supplies can be used in printers or other fluid ejection mechanisms. Fluid supplies may contain capillary material to hold the fluid under a suitable back pressure. Certain fluid supplies are replaceable with respect to corresponding fluid ejection devices. Certain examples of replaceable fluid supplies have a head land containing fluid ejection actuators for ejecting the fluid directly from the replaceable fluid supply onto a substrate. Other examples of replaceable fluid supplies are arranged to be connected to a fluid ejection head containing fluid ejection actuators present in the fluid ejection device. Some fluid supply housings contain fluid slots for supplying the fluid, for example either directly to a substrate or to a fluid ejection head land for subsequent ejection. The fluid supply housings are provided with chambers for holding the fluid and channels to deliver the fluid to the fluid slots.